The present invention relates to a rotor, a method for producing a rotor, an asynchronous machine and a vehicle. The present invention relates, in particular, to a rotor for an asynchronous machine, a method for producing a rotor for an asynchronous machine, an asynchronous machine, in particular for a drive of a vehicle, and a vehicle, in particular a passenger car and/or a hybrid vehicle.
In many technical applications, in particular when driving vehicles and their components, asynchronous machines are used. Such machines are also referred to as three-phase asynchronous machines or three-phase induction machines. In such machines, a rotor and a stator interact with one another via rotational magnetic fields, wherein in the generator mode the rotor leads the stator rotational field, and in the motor mode the rotor lags the stator rotational field.
In passive asynchronous machines, the rotor is formed by a short-circuit rotor or cage rotor. Such a rotor is composed of a laminated core, in particular of an iron laminated core with grooves formed in it, wherein the laminations are electrically insulated from one another. Rods are usually introduced into the grooves in the laminated core during production and electrically short-circuited via short-circuit rings, which can be done by means of a casting process.
It is problematic that substitution of materials in order to improve the electrical conductance values, on the one hand, and increasing the mechanical stability, on the other, cannot be carried out with known production methods, or can only be carried out with considerable additional expenditure in terms of material and energy costs.
The invention is based on the object of specifying a rotor for an asynchronous machine which makes the design and the operation of an asynchronous machine more reliable without increasing the expenditure during production. In addition, the invention is based on the object of specifying a corresponding production method for a rotor, an asynchronous machine and a vehicle and of developing it correspondingly.
The object on which the invention is based is achieved according to the invention with a rotor for an asynchronous machine, a method for manufacturing a rotor for an asynchronous machine, an asynchronous machine so provided, and a vehicle with the asynchronous machine, in accordance with embodiments of the invention.
A rotor according to the invention for an asynchronous machine has a laminated core and a short-circuit cage (also known as a “squirrel” cage) which is at least partially integrated into the laminated core. In the case of the rotor according to the invention, the short-circuit cage is constructed with rods made with or from a first electrically conductive material and short-circuit rings made with or from a second electrically conductive material. The short-circuit rings are constructed with an indirect or direct friction-welded connection to the rods. Owing to the friction-welded connection between the short-circuit rings and the rods of the short-circuit cage, the rotor can be developed in a particularly flexible way with respect to the first and second materials used for the rods and/or the short-circuit rings without additional expenditure with respect to the consumption of energy and materials. A connection between the material of the rods of the short-circuit cage and the short-circuit rings is carried out in a simple way by the friction-welded connection, with the result that additional expenditure in terms of energy or costs, for example in conjunction with a casting process, is eliminated.
In one advantageous development of the rotor according to the invention, the rods of the short-circuit cage have a cast and/or joined structure.
Alternatively or additionally, one or more of the short-circuit rings, in particular all the short-circuit rings, can be constructed as end rings of the short-circuit cage.
In particular, a structure is possible which has exclusively two short-circuit rings, specifically in the form of end rings.
Owing to the possibility of the more flexible selection of materials for the materials of the rods of the short-circuit cage, on the one hand, and of the short-circuit rings, on the other, according to a further development of the rotor according to the invention it is possible for the first material to have a higher electrical conductivity than the second material.
Alternatively or additionally, the second material can have greater mechanical strength and/or stability than the first material.
In this context, a careful selection of the materials in combination with one another can improve overall both electrical properties and the mechanical integrity of the rotor according to the invention.
Therefore, according to one development of the rotor according to the invention, it is contemplated for the first material and/or the second material to be a material from the group which comprises aluminum, copper, silver and alloys thereof, and in particular the first material is or has copper or a copper alloy, and the second material is or has aluminum or an aluminum alloy.
In order to improve the electrical contact between the rods of the short-circuit cage and the short-circuit rings and/or in order to suppress corrosion problems, according to a particularly preferred embodiment of the rotor according to the invention it is contemplated that at least one deflector plate is constructed. The at least one deflector plate is arranged between the rods and one of the short-circuit rings and is connected in an electrically conductive fashion to the rods and the short-circuit ring, wherein the connection of the at least one deflector plate to the at least one short-circuit ring is a friction-welded connection.
According to another aspect of the present invention, a method for manufacturing a rotor for an asynchronous machine is provided.
In terms of processing technology, the present invention is based on the fact that a rotor for an asynchronous machine, comprising a laminated core and a short-circuit cage which is at least partially integrated into the laminated core, is processed. The short-circuit cage is constructed with rods made with or from a first electrically conductive material and short-circuit rings made with or from a second electrically conductive material. The short-circuit rings are constructed with an indirect or direct friction-welded connection to the rods.
The production method according to the invention for the rotor can also be developed in an analogous fashion to the structural advantages of the rotor according to the invention for an asynchronous machine.
It is therefore possible for the rods of the short-circuit cage to be cast and/or joined.
Alternatively or additionally thereto, one or more short-circuit rings can be constructed as end rings.
In order to improve the electrical properties and/or the mechanical integrity of the rotor according to the invention overall, in one development of the production method according to the invention there is provision that a material with a higher electrical conductivity than that of the second material is used as the first material, and/or that a material with greater mechanical strength and/or stability than that of the first material is used as the second material.
In this context, in particular a material from the group which comprises aluminum, copper, silver and alloys thereof can be used as the first material and/or as the second material. In particular copper or a copper alloy can be used as the first material and/or aluminum or an aluminum alloy can be used as the second material.
In order to improve the electrical properties and to avoid corrosion problems with the rotor to be processed for an asynchronous machine, in one development of the production method according to the invention there is provision that at least one deflector plate is constructed. The at least one deflector plate is arranged between the rods and one of the short-circuit rings and is connected in an electrically conductive fashion to the rods and the short-circuit ring and the connection of the at least one deflector plate to the at least one short-circuit ring is constructed by friction welding.
According to a further aspect of the present invention, an asynchronous machine is provided, in particular for the drive and/or as a generator of a vehicle. The asynchronous machine according to the invention comprises a rotor and a stator, wherein the rotor has the structure according to the invention.
In addition, the present invention also provides a vehicle, in particular a passenger car, a battery-powered electric vehicle and/or a hybrid vehicle which has an asynchronous machine which is configured according to the invention and is constructed as part of a drive and/or of a generator of the vehicle.
The asynchronous machine according to the invention can also be used in any other devices as a drive and/or as a generator component, e.g. in working machines or machine tools, in particular in a circular saw, in pumps, e.g. water pumps, in hydraulic generators and wind-powered generators and the like.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.